具有单调功能反应的离散时间比率依赖的捕食——被捕食系统的持久性

通过运用差分方程的比较原理,获得具有单调功能反应的离散时间比率依赖的捕食-被捕食模型持久性的充分条件.     

比率依赖型捕食扩散模型的一个注记

讨论了在齐次Neumann边界条件下具有比率依赖型捕食反应扩散模型.应用比较原理和建立与正解的上下确界相关的迭代格式,得到了一些改进的结果,即惟一的正常数平衡态是全局渐近稳定的.该结果说明了2种群最终在空间上均匀分布.所提出的方法也适用于其他一些模型.应用于讨论一些反应扩散系统非正常数平衡态的不存在性,该方法相当简单但是十分有效.     

一类比率依赖的捕食模型平衡解的局部分歧

研究了一类比率依赖的捕食模型平衡解的分歧.利用特征值和分歧理论,证明了系统在半平凡解附近出现的分歧现象,得到了正解存在的充分条件.     

一类基于比率的Leslie时滞捕食-食饵模型的持久性

利用微分方程比较原理探讨了周期情形下一类基于比率的Leslie时滞捕食-食饵模型的持久性,补充和完善了梁志清、陈兰荪和高建国等学者的工作.     

一类基于比率依赖的捕食-食饵模型的定性分析

研究了一类两物种间的捕食—食饵模型,其功能反映函数为比率依赖型.首先运用抛物型方程的比较原理得到系统的一个全局吸引子,然后通过椭圆型方程的极值原理和特征值方法对平衡态解的性质加以分析.最后证明了共存解的存在性和稳定性.     

具有比率依赖功能反应和阶段结构捕食系统的持久性与周期性

研究了一类具有功能反应和阶段结构的捕食模型。在此系统中食饵分幼年和成年两个阶段,捕食者仅捕食幼年食饵,并且考虑食饵和捕食者之间具有比率依赖功能反应。利用一些引理和比较定理,讨论系统在一定条件下的周期性和持久性。     

一类基于定比率的捕食-食饵模型的非常数正平衡解

研究了一类基于定比率和具有第三类功能性反应的捕食-食饵模型.主要讨论了常数解的稳定性及正平衡解的先验估计,给出了非常数正平衡解不存在条件,同时利用度理论研究了非常数正平衡解的存在性条件.     

一类三种群离散捕食系统的稳定性

通过构造适当的Lyapunov函数,建立了一类基于比率且具有Machaelis-Menten型功能性反应的三种群离散捕食系统正解稳定性的充分条件。     

一类三种群离散捕食系统的持久性

利用差分比较原理讨论一类基于比率且具有Machaelis-Menten型功能性反应的三种群离散捕食系统持久性,得到了该系统持久生存的充分条件。补充了一些学者的工作。     

成年食饵具有扩散的捕食系统周期解

构造一类成年食饵具有扩散的比率依赖型时滞捕食系统,利用Gaines—Mawhin’S重合度原理,推导了该系统周期解的存在性．     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.